I have a 1985 cn250 Helix.Hasn't run for a while... so I bought a new carburetor for it and installed it.Machine starts and idles just fine. When I go out on a test drive everything runs great. Then it quits like it is out of gas. Cannot Start. After sitting for several minutes it starts and run perfect. Then repeats above.

Spark plug Looks good.When it runs it run smooth and no backfires. Sounds like it is getting correct amount of gas. It will idle for like 10-15 minutes no problem. Then I take it out and within the first mile it quits and have to wait a while before it will turn over and run.Almost like the fuel bowl is filling up and you drive it and the fuel is used up then after waiting a while the fuel bowl gets refilled and it starts just fine.

sbrowerslc wrote:I have a 1985 (1995?) cn250 Helix. Hasn't run for a while... so I bought a new carburetor for it and installed it. Machine starts and idles just fine. When I go out on a test drive everything runs great. Then it quits like it is out of gas. Cannot Start. After sitting for several minutes it starts and run perfect. Then repeats above. Checked fuel and it is present. Any ideas where/what I can look for ?

As the other poster asked what kind (manufacturer) of new carburetor did you install? If it's a cheap chinese one, you're in trouble.

I recommend that you run a fuel pump fuel flow capacity test as indicated in manual 12-10. I'm not convinced it's the fuel pump.

Usually, whe you have start ups and continuous runs for 15 minutes then sudden cut offs, that leads me to believe that there are issues possibly with the coil wire, coil itself, o-ring missing/ cut on the rear side of the intake boot, or CDI flow cracks.

Change the spark plug to eliminate a simple fix. My father was having this same issue with a pressure washer. It would die shortly after starting and he replaced carb, fuel pump, and a couple other things. Turns out the ceramic inside the plug was cracked but the plug would test fine when cold and run fine when cold. When it heated up the crack would expand and kill the spark. Replaced the plug and all is well. It’s worth a try.

Agree with Av8er, my Honda push mower did the same thing. Couldn't figure it out. Took it to repair shop, and was surprised when they called and said all it needed was a new spark plug. Has run fine since..